Commercial airplanes include thermal and acoustic insulation materials to meet requirements for thermal, acoustic and moisture management within the pressurized cabin. Typically, airplanes utilize thermal/acoustic insulation blankets, which are placed adjacent to the interior skin of the aircraft's fuselage, between fuselage structural frame members. The insulation blankets are typically constructed of a fibrous lofted insulation material, such as fiberglass batting, foam or other buildups encased within protective covering films, and are suitably sized to fit snugly between the fuselage frame members and are fastened to the frame members by spring clamps or clips.
Any thermal/acoustic insulation materials, including the means of fastening the insulation materials to the fuselage, must meet certain criteria defined by the Code of Federal Regulations, particularly 14 C.F.R. §25 (also referred to as FAR Part 25). For example, the insulation blankets and fastening clamps must meet flame penetration resistance test requirements (25.856(a)) or burnthrough requirements (25.856(b)) as defined by the CFR. Additionally, the fastening clamps must meet certain corrosion resistance properties.
To meet current burnthrough and corrosion resistance requirements, insulation clamps typically utilize stainless spring steel or other aerospace steels. Such steel insulation clamps account for unnecessary weight and cost to the production of airplanes. Nylon or polyether ether ketone (PEEK) clamps do not have the retention properties of spring steel and may lose their shape over time. Carbon steel cannot be heat-treated and is also heavy and expensive.
Accordingly, those skilled in the art continue with research and development efforts in the field of airworthiness standards related to fire penetration and resistance.